Ultraviolet LED packaging structure with high luminous efficiency and high utilization rate for printing and curing

Abstract

The invention discloses an ultraviolet LED packaging structure with high luminous efficiency and high utilization rate for printing and curing, which comprises a packaging bracket, the periphery of the surface of the packaging bracket extends upwards to form a bulge with two table tops, the bulge comprises a first table top and a second table top, a packaging lens is arranged above the surface of the second table top, and the packaging lens is arranged above the surface of the packaging bracket. A filling layer is formed on the object carrying surface between the packaging lens and the packaging support, and the filling layer is internally provided with an LED chip and is filled with fluorine oil. The interface reflection loss is reduced, the stability of light transmittance is high, the service life is prolonged, and the light utilization rate and the light emitting efficiency of the light source are improved.

Description

Technical Field

[0001] This application relates to the field of LED packaging structure technology, specifically to a UV LED packaging structure for printing and curing that combines high luminous efficiency and high utilization rate. Background Technology

[0002] In the printing industry, ultraviolet LED (UV LED) light sources are needed to cure UV inks and varnishes on the surface of printed materials. This requires a significant increase in the luminous efficiency and light utilization of UV LED light sources, especially UVC sources. A key factor affecting the light extraction efficiency of UV LEDs is the interface reflection between the LED chip surface and the encapsulation lens surface. To reduce the loss of light emission due to interface reflection, a material can be injected between the LED chip and the encapsulation lens to eliminate air gaps, thereby improving the light extraction efficiency. This reduces light energy loss by approximately 8% due to two fewer interface reflections during propagation (approximately 4% improvement per interface); compared to ordinary UV LED light source packaging, its luminous efficiency is about 8% higher.

[0003] However, UVC light has a very high photon bond-breaking energy, and the main wavelength of UVC light sources used for printing and curing is generally above 254nm: according to the photon bond-breaking energy formula E=1.196×10⁵ / λ, the bond-breaking energy of 254nm UV light is 470.8 kJ / mol. Silicone and silicone oil, commonly used in LED packaging, have Si-O bonds with a bond energy of 460.5 kJ / mol, which cannot meet the lifespan requirements of UVC light sources used for printing and curing. Under long-term high-temperature conditions, silicone and silicone oil undergo aging and degradation, reducing the transmittance of the UVC light source and shortening its lifespan.

[0004] Currently, LED chips are arranged in a rectangular structure, which leads to light spot segmentation during the later curing process, affecting light intensity concentration and reducing the utilization rate of the light source during curing. Simultaneously, there is a gap between the LED chip and the encapsulating lens. Silicone or silicone oil is filled into this gap to improve overall light extraction efficiency. However, during filling, it is difficult to control the amount of filler, resulting in filler overflow and some gas in the filler layer not escaping easily, causing air bubbles inside the filler layer and affecting light extraction efficiency.

[0005] Therefore, this application is submitted. Summary of the Invention

[0006] The purpose of this invention is to provide a UV LED packaging structure for printing and curing that combines high luminous efficiency and high utilization rate. Fluorine oil is selected as the main filler material, the arrangement structure of the LED chip is changed and an overflow groove is set, which solves the problems of aging and cracking of existing fillers, reduced light transmittance and shortened lifespan, while improving the light utilization rate and light output efficiency of optical fibers.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following solution: A UV LED packaging structure for printing and curing that combines high luminous efficiency and high utilization rate includes a packaging bracket, and a protrusion with two mezzanines extending upward around the perimeter of the packaging bracket surface. The protrusion includes a first mezzanine and a second mezzanine. A packaging lens is disposed above the surface of the second mezzanine. A filling layer is formed between the packaging lens and the packaging bracket. An LED chip is disposed inside the filling layer and filled with fluorinated oil.

[0008] Fluorinated oil is a perfluoropolyether (PFPE), and the bond energy of the CF bond in the fluorinated oil is at least 485 kJ / mol, with a refractive index of at least 1.38. This allows it to resist chemical bond breakage under ultraviolet light, resulting in a significantly longer lifespan than silicone and silicone oil. The high bond energy of the CF bond gives the fluorinated oil high chemical inertness, making it resistant to strong acids and alkalis, oxidation-resistant, protecting LED chip electrodes from oxidation, and providing high thermal stability. Its decomposition temperature is typically greater than 300℃. Furthermore, the CF bond has no significant absorption in the ultraviolet band, making it less prone to photodecomposition and improving light transmittance.

[0009] Furthermore, the bond energy of the CF bond in the fluorinated oil is at least 485 kJ / mol, and the refractive index is at least 1.38.

[0010] Furthermore, the LED chips are arranged in a uniform line at the center of the filling layer, and the encapsulation lens includes a vertical segment at the bottom and a curved segment at the top, the surface of which has a continuous curve.

[0011] Furthermore, there is a gap between adjacent LED chips, with a gap of 0.2mm to 0.4mm.

[0012] Furthermore, the bottom surface of the vertical segment, the second platform, and the upper surface of the filling layer are on the same medium connection surface.

[0013] Furthermore, the vertical section is higher than the first platform, and there is a gap between the side of the vertical section and the inner wall of the first platform.

[0014] Furthermore, the inner sidewall of the first platform is provided with an overflow groove for filling the excess fluorinated oil that overflows from the second platform, and the overflow groove surrounds the encapsulated lens.

[0015] Furthermore, the overflow trough is higher than the medium connection surface.

[0016] Furthermore, the gap above the overflow trough is filled with sealant.

[0017] Furthermore, the width of the first tabletop is smaller than the width of the second tabletop.

[0018] The beneficial effects of this invention are as follows: Firstly, the present invention uses fluorinated oil as the filler in the filling layer. Its refractive index is between that of the LED chip and the encapsulation lens made of quartz glass, which reduces interface reflection loss, improves the light output efficiency of the UVC light source, and has high transmittance stability. Fluorinated oil can resist the breaking of chemical bonds by ultraviolet light, extend the service life of the LED chip, protect the LED chip electrodes from oxidation, and has high thermal stability, making it less prone to photodecomposition.

[0019] Secondly, the LED chips are arranged in a uniform line inside the filling layer and are assembled with the encapsulation lens, which has a vertical section at the bottom and a curved section at the top. The light travels directly from the surface of the LED chip through the vertical section to the surface of the curved section, is transmitted and then refracted, and then reaches the working area through the secondary light distribution lens, so that the light is concentrated into a strip-shaped light spot without light splitting, thereby improving the light utilization rate of the UVC light source.

[0020] Thirdly, by setting an overflow groove on the inner sidewall of the first protrusion, excess fluorinated oil flows into the overflow groove. During the flow process, the air in the filling layer flows first, thereby reducing the residual air in the filling layer, resulting in high light extraction efficiency and eliminating the need to control the amount of fluorinated oil used. The gap above the overflow groove is filled with sealant to prevent liquid fluorinated oil from leaking through the gap above the overflow groove, thus enhancing the sealing performance of the liquid fluorinated oil. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a cross-sectional structural diagram of the present invention; Figure 3 This is a top-sectional view of the structure of the present invention; Figure 4 This is a partially enlarged structural diagram of the overflow trough after encapsulation in this invention; Figure 5 This is a schematic diagram of the light transmission / refraction path of the non-circular packaged lens and the circular packaged lens of the present invention. A represents the non-circular packaged lens, and B represents the circular packaged lens. Figure 6 Simulated light spot pattern after light distribution of conventional rectangular array chips; Figure 7 This is a simulated light spot diagram after the chip of the present invention is light-distributed.

[0022] Reference numerals: 1-Encapsulation bracket, 2-Protrusion, 20-First platform, 21-Second platform, 3-Encapsulation lens, 30-Vertical segment, 31-Curved segment, 4-LED chip, 5-Filling layer, 50-Fluorine oil, 6-Overflow groove, 7-Sealant. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention.

[0025] At the same time, it should be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn according to actual scale.

[0026] Furthermore, for clarity and brevity, descriptions of well-known structures, functions, and configurations may have been omitted. Those skilled in the art will recognize that various changes and modifications can be made to the examples described herein without departing from the spirit and scope of this disclosure.

[0027] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0028] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0029] Example 1 A UV LED packaging structure for printing and curing that combines high luminous efficiency and high utilization rate includes a packaging bracket 1, and a protrusion 2 with two platforms extending upward around the perimeter of the packaging bracket 1. The protrusion 2 includes a first platform 20 and a second platform 21. A packaging lens 3 is disposed above the surface of the second platform 21. A filling layer 5 is formed on the carrier surface between the packaging lens 3 and the packaging bracket 1. An LED chip 4 is disposed inside the filling layer 5 and filled with fluorinated oil 50.

[0030] In this invention, the LED chip 4 is primarily a UVC light source, and the fluorinated oil 50 is perfluoropolyether (PFPE). The CF bond energy in the fluorinated oil 50 is at least 485 kJ / mol, and the refractive index is at least 1.38, which resists chemical bond breakage under ultraviolet light, resulting in a significantly longer lifespan than silicone and silicone oil. The high bond energy of the CF bond gives the fluorinated oil 50 high chemical inertness, making it resistant to strong acids and alkalis, oxidation-resistant, protecting the LED chip 4 electrodes from oxidation, and providing high thermal stability. Its decomposition temperature is typically greater than 300℃. Furthermore, the CF bond has no significant absorption in the ultraviolet band, making it less prone to photodecomposition.

[0031] In addition, the refractive index of fluorinated oil 50 is between that of LED chip 4 and encapsulation lens 3 made of quartz glass, which can reduce interface reflection loss and improve light output efficiency by about 8%. At the same time, its lifespan is >10,000h, light transmittance is greater than 95%, and light efficiency stability is high. On the other hand, silicone or silicone oil is used as filler, which will cause aging and cracking after long-term use, resulting in a lifespan of 500~2000h, initial light transmittance <90%, and light transmittance of 70% after aging and cracking.

[0032] Example 2 The purpose of this embodiment 2 is to solve the problem of light spot segmentation affecting light intensity concentration in conventional rectangular LED chip arrangements during use. The LED chips 4 are arranged uniformly in a straight line at the center of the filler layer 5. The encapsulation lens 3 includes a vertical segment 30 at the bottom and a curved segment 31 at the top, with the surface of the curved segment 31 having a continuous curve. Adjacent LED chips 4 are spaced apart by a distance of 0.2mm to 0.4mm.

[0033] Specifically, when LED chip 4 is powered on and emits light, the emitted light travels directly from the surface of LED chip 4 to the surface of encapsulation lens 3. Encapsulation lens 3 (which has a non-circular structure) distributes the light emitted from LED chip 4. The light is first transmitted inside encapsulation lens 3, then refracted along a continuous curve on its surface, and finally reaches the predetermined working area through a secondary light distribution lens, ultimately focusing the light into a strip-shaped light spot. Figures 1 to 5 A, where Figure 5 B uses a semi-circular encapsulated lens, allowing light to be transmitted directly outward without refraction, thus preventing light dispersion. The spacing makes the light emitted by the LED chip 4 more uniform after being powered on, and the center line of each LED chip 4 coincides with the center line of the filling layer 5, ensuring the position of the LED chip 4 inside the filling layer 5 and ensuring the concentration of light.

[0034] The curvature of the continuous curve of the curved surface segment 31 here is designed using the imaging optical design software Zemax through optical function equations, based on the size and position of different LED chips 4. This is existing technology and will not be elaborated here.

[0035] In some preferred embodiments, the bottom surface of the vertical section 30, the second platform 21, and the upper surface of the filling layer 5 are on the same medium connection surface. The vertical section 30 is higher than the first platform 20, and there is a gap between the side of the vertical section 30 and the inner wall of the first platform 20. The medium connection surface is the medium connection surface formed by the fluorinated oil 50 between the bottom surface of the vertical section 30 and the second platform 21, and between the bottom surface of the vertical section 30 and the filling layer 5 after the fluorinated oil 50 is filled.

[0036] Meanwhile, the vertical segment 30 has a rectangular cross-section, and the length of the curved segment 31 is consistent with the length of the vertical segment 30. That is, the curved segment 31 has multiple vertices, among which are multiple points coaxial with several LED chips 4. When any LED chip 4 emits light, the light passes through the interior of the encapsulation lens 3, is refracted outwards through the surface formed by its continuous curves, and reaches the designated working area through the secondary light-distributing lens. Figure 5 A and Figure 7 This ultimately forms a concentrated stripe of light, improving the utilization rate of the light source during printing and curing, and increasing curing efficiency; it also solves the problem of light spot segmentation in conventional rectangular LED chip arrangements in existing technologies, referring to... Figure 6 .

[0037] Meanwhile, the vertical section 30 is lower than the first platform 20, which can prevent the fluorinated oil 50 in the gap from contacting the surface of the curved section 31, thus preventing the light source from scattering and affecting its function. The curvature of the curved section 31 can be set according to the specific specifications of the LED chip 4, which is existing technology and will not be described in detail here.

[0038] Example 3 The purpose of this embodiment 3 is to prevent air in the fluorine oil 50 from forming bubbles in the filling layer 5 during filling, which would affect the light output efficiency. The inner sidewall of the first platform 20 is provided with an overflow groove 6 for filling the filling layer 5 and overflowing excess fluorine oil 50 through the second platform 21, and the overflow groove 6 surrounds the encapsulated lens 3.

[0039] Specifically, during the assembly of the encapsulated lens 3, the bottom surface of the vertical section 30 of the encapsulated lens 3 will contact the second platform 21. Excess fluorinated oil 50 first flows through the gap between the second platform 21 and the bottom surface of the vertical section 30 into the gap between the inner wall of the first platform 20 and the vertical section 30 (this gap is lower than the overflow trough 6). At this time, the excess fluorinated oil 50 enters the ring-shaped overflow trough 6. After the overflow trough 6 is filled with fluorinated oil 50, the excess fluorinated oil 50 in the gap between the second platform 21 and the bottom surface of the vertical section 30, the excess fluorinated oil 50 in the gap below the overflow trough 6, and the excess fluorinated oil 50 in the overflow trough 6 are combined into one.

[0040] In some preferred embodiments, the overflow trough 6 is higher than the medium connection surface. When the encapsulated lens 3 is installed, the encapsulated lens 3 squeezes the fluorinated oil 50 inside the filling layer 5 to overflow outward. During this process, air will flow outward from the gap between the filling layer 5 and the encapsulated lens 3. The overflow trough 6 is higher than the bonding surface between the encapsulated lens 3 and the filling layer 5 so that the fluorinated oil 50 flowing into the overflow trough 6 can be refluxed by gravity and undergo a secondary displacement in the filling layer 5.

[0041] Meanwhile, the longitudinal section of the overflow trough 6 is square or rectangular. Setting it to a rectangle can better fill the gap between the second table surface 21 and the bottom surface of the vertical section 30, as well as the gap below the overflow trough 6, without the need to control the amount of fluorinated oil 50 used, and at the same time remove air bubbles contained in the filling layer 5.

[0042] In some preferred embodiments, the gap above the overflow trough 6 is filled with sealant 7. Since the fluorinated oil 50 is liquid, it can fill all gaps without dead angles, making the elimination of air bubbles more thorough; no curing is required during the filling process of the fluorinated oil 50, avoiding damage to the LED chip 4 due to curing shrinkage stress. Furthermore, after the fluorinated oil 50 is filled, a liquid sealing layer is formed at the filling layer 5 and the overflow trough 6. Simultaneously, the gap above the overflow trough 6 is filled with sealant 7. After the sealant 7 cures, it seals the gaps at the first platform 20 and the vertical section 30, thereby preventing the liquid fluorinated oil 50 from leaking through the gap above the overflow trough 6. (Refer to...) Figure 4 .

[0043] In some preferred embodiments, the width of the first platform 20 is smaller than the width of the second platform 21. The second platform 21 is mainly used to support the bottom surface of the vertical section 30 of the encapsulated lens 3, providing a load-bearing function for the bottom surface of the vertical section 30, thereby ensuring the secure installation of the encapsulated lens 3 above the second platform 21.

[0044] The working principle of this invention is as follows: First, several encapsulation lenses 3 are selected according to the length of the encapsulation lens 3 and the filling layer 5, and LED chips 4 are arranged in a uniform line at the center of the filling layer 5. Then, according to the specific selection of the chip, an encapsulation lens 3 that is adapted to the curved section 31 is selected. Due to the curved section 31 at the top and the vertical section 30 at the bottom, light is transmitted directly from the surface of the LED chip 4 through the vertical section 30 to the interior of the curved section 31 for transmission. The light is refracted outward upon reaching the surface composed of continuous curves, and reaches the predetermined working area through the secondary light distribution lens, so that the light is concentrated into a strip-shaped light spot without light splitting, thereby improving the light utilization rate of the light source. Fluorine oil 50 is filled to a position slightly higher than the filling layer 5, and the encapsulation lens 3 is pressed downward. Excess fluorine oil 50 will flow into the gap between the second platform 21 and the bottom surface of the vertical section 30 of the encapsulation lens 3, and then flow into the gap below the overflow tank 6 and the interior of the overflow tank 6. During this process, since the air mass is less than that of the fluorinated oil 50, the air outflow priority is greater than that of the fluorinated oil 50. Therefore, the air in the filling layer 5 will flow into the overflow tank 6 first. Then, the excess fluorinated oil 50 mixed with air will flow into the gap below the overflow tank 6 through the gradually narrowing gap between the second platform 21 and the bottom surface of the vertical section 30, continuing to press down on the encapsulated lens 3 until it is completely adhered to the filling layer 5. The excess fluorinated oil 50 will flow into the overflow tank 6 through the gap below the overflow tank 6, reducing the air residue in the filling layer 5. There is no need to control the amount of fluorinated oil 50. At the same time, the gap above the overflow tank 6 is filled with sealant 7. After the sealant 7 cures, it seals the gap between the first platform 20 and the vertical section 30. Using fluorinated oil 50 as a filler extends the service life of the LED chip 4, protects the electrodes of the LED chip 4 from oxidation, and has high thermal stability. It is not easy to undergo photodecomposition and has high light transmittance stability.

[0045] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A UV LED packaging structure for printing and curing that combines high luminous efficiency and high utilization rate, characterized in that, The package includes a packaging bracket (1), and a protrusion (2) with two platforms extending upward around the surface of the packaging bracket (1). The protrusion (2) includes a first platform (20) and a second platform (21). A packaging lens (3) is disposed above the surface of the second platform (21). A filling layer (5) is formed between the packaging lens (3) and the packaging bracket (1). An LED chip (4) is disposed inside the filling layer (5) and filled with fluorinated oil (50).

2. The UV LED packaging structure for printing and curing with high luminous efficiency and high utilization rate according to claim 1, characterized in that, The CF bond energy in the fluorinated oil (50) is at least 485 kJ / mol, and the refractive index is at least 1.

38.

3. The UV LED packaging structure for printing and curing with high luminous efficiency and high utilization rate according to claim 1, characterized in that, The LED chips (4) are arranged in a uniform line at the center of the filling layer (5), and the encapsulation lens (3) includes a vertical segment (30) at the bottom and a curved segment (31) at the top, the surface of which has a continuous curve.

4. The UV LED packaging structure for printing and curing with high luminous efficiency and high utilization rate according to claim 3, characterized in that, Adjacent LED chips (4) are spaced apart by a distance of 0.2 mm to 0.4 mm.

5. The UV LED packaging structure for printing and curing with high luminous efficiency and high utilization rate according to claim 3, characterized in that, The bottom surface of the vertical section (30), the second platform (21), and the upper surface of the filling layer (5) are on the same medium connection surface.

6. The UV LED packaging structure for printing and curing with high luminous efficiency and high utilization rate according to claim 5, characterized in that, The vertical section (30) is higher than the first tabletop (20) and there is a gap between the side of the vertical section (30) and the inner wall of the first tabletop (20).

7. The UV LED packaging structure for printing and curing with high luminous efficiency and high utilization rate according to claim 5, characterized in that, The inner wall of the first platform (20) is provided with an overflow groove (6) for filling the filler layer (5) to overflow excess fluorine oil (50) through the second platform (21), and the overflow groove (6) surrounds the encapsulated lens (3).

8. The UV LED packaging structure for printing and curing with high luminous efficiency and high utilization rate according to claim 7, characterized in that, The overflow trough (6) is higher than the medium connection surface.

9. A UV LED packaging structure for printing and curing that combines high luminous efficiency and high utilization rate according to claim 7, characterized in that, The gap above the overflow trough (6) is filled with sealant (7).

10. A UV LED packaging structure for printing and curing that combines high luminous efficiency and high utilization rate according to claim 7, characterized in that, The width of the first tabletop (20) is smaller than the width of the second tabletop (21).

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